One type of known of blood vessel insertion balloon catheter is a catheter used for PTCA (Percutaneous Transluminal Coronary Angioplasty), hereinafter referred to as a “PTCA catheter.” In this catheter, a guide wire lumen for passing a guide wire therethrough is formed over the whole length of the catheter, in addition to the lumen for expanding a balloon. The catheter is inserted into a blood vessel in the condition where the guide wire is inserted in the guide wire passing lumen and the distal portion of the guide wire protrudes from the catheter.
To perform PTCA, a plurality of PTCA catheters differing in the outside diameter of the catheter shaft and in the outside diameter of the balloon in its expanded state are prepared. In some cases, catheter replacement is conducted after a first catheter is inserted into a blood vessel. The catheter replacement is preferably conducted while the guide wire is left indwelling in the blood vessel, from the viewpoint of reducing the burden on the patient, reducing operation time and labor, preventing infection, etc. In catheters referred to as rapid exchange type catheters, a port for insertion of the guide wire is formed not at the proximal end of the catheter but in a side surface on the distal side of the catheter. In this catheter, therefore, catheter replacement can be easily carried out while the guide wire is left indwelling in the blood vessel.
A known rapid exchange type catheter is disclosed in JP-A-Hei 6-507105 (WO 93/15786). In this catheter, to reinforce an insertion port for insertion and drawing-out of the guide wire, a reinforcing core wire is joined to a distal portion of a proximal shaft formed of a high-rigidity material such as a metal, and the core wire is extended to the distal side relative to the insertion port portion.
However, with the structure disclosed in JP-A-Hei 6-507105 (WO 93/15786), the core wire is processed as a member separate from the proximal shaft portion, and thereafter the processed core wire is joined to a distal portion of the proximal shaft portion by brazing or a like method. Thus, the assembling operation is intricate.
In view of this, Japanese Patent Laid-open No. 2001-95924 proposes a catheter in which a reinforcement portion is formed by reducing the diameter of a portion near the distal end of the proximal shaft to reinforce the insertion port portion with the reinforcement portion.
On the other hand, a catheter construction is disclosed in JP-A-Hei 10-503386 (WO 95/28197) in which the distal portion of the core wire is embedded in the tube wall of the shaft for the purpose of efficiently transmitting a pushing force exerted on the proximal shaft to the distal end of the catheter.
However, with the catheter disclosed in JP-A-Hei 10-503386 (WO 95/28197), a step of embedding the distal portion of the core wire into the tube wall is carried out after the step of inserting the core wire into the shaft. This thus requires a rather intricate manufacturing process.